Artificial limbs

ABSTRACT

AN ARTICULATED ARTIFICIAL LIMB HAVING TWO PIVOTALLYCONNECTED LIMB MEMBERS REPRESENTING, FOR EXAMPLE, THE UPPER ARM AND THE FORE-ARM RESPECTIVELY OF A HUMAN ARM, THE TWO LIMB MEMBERS BEING FURTHER LINKED TOGETHER BY A TELESCOPIC LINK HAVING A READILY-RELEASABLE LOCKING DEVICE TO PERMIT THE ANGLE BETWEEN THE TWO LIMB MEMBERS TO BE VARIED AS REQUIRED.

NOV. 16, 1971 w, co s 3,619,818

ARTIFIC IAL LIMBS Filed Oct. 1, 1969 MWE/VTOR. DE/VN/S WM 4 l/IM c 04 4//v.s',

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United States Patent 3,619,818 ARTIFICIAL LIMBS Dennis W. Collins,Kingston-upon-Thames, England, as-

signor to Hugh Steeper (Roehampton) Limited, London, England Filed Oct.1, 1969, Ser. No. 862,667 Claims priority, application Great Britain,Oct. 3, 1968, 47,045/ 68 Int. Cl. A61f 1/06 US. Cl. 312 2 ClaimsABSTRACT OF THE DISCLOSURE An articulated artificial limb having twopivotallyconnected limb members representing, for example, the upper armand the fore-arm respectively of a human arm, the two limb members beingfurther linked together by a telescopic link having a readily-releasablelocking device to permit the angle between the two limb'members to bevaried as required.

This invention relates to articulated artificial limbs having two limbmembers pivotally connected together for relative pivotal movement. Itis especially applicable to articulated artificial arms which compriseupper and lower limb members pivotally connected together for relativepivotal movement to simulate the way in which the upper and lower partsof a human arm pivot about the elbow joint.

It has already been proposed to provide an articulated artificial armwhich has a ratchet and a half-portion of a ratchet wheel at the pivotalconnection between the two limb members. This construction, however, hasthe disadvantage that it cannot be easily controlled by the wearer ofthe artificial arm.

The main aim of the present invention therefore is to provide anarticulated artificial limb having two limb members which includesimproved means for locking one of the limb members in a number ofangular positions in relation to the other limb member, and according tothe invention the two limb members, in addition to being pivotallyconnected together for relative pivotal movement, are further linkedtogether by a telescopic link comprising a pair of telescoped elementsand a readily-releasable locking device which is operable to lock thetelescoped elements in a number of different relative axial positions,thereby locking the two limb members in a corresponding number ofrelative angular positions.

Where the invention is applied to an artificial arm having an upper limbmember and a lower limb member, the telescopic link preferably extendsfrom a point in the upper limb member some two or three inches above thepivotal connection with the lower limb member to a point about halfwayalong the lower limb member. Because of the relative pivotal movementwhich is provided between the two limb members, the telescopic link isconnected at each of its ends to the respective limb members by someform of pivotal attachment.

The locking device whereby the telescoped elements of the telescopiclink can be locked in a number of different relative axial positions cantake several different forms, but it preferably comprises one or morelocking balls located in the outer telescopic element and arranged toseat in any one of a number of transverse or annular grooves providedalong that portion of the inner telescopic member which slides in theouter telescopic member. A spring or some other biasing member isprovided so as to cause the two telescoped elements to be urged into aposition where they are locked against relative axial movement by thelocking ball or balls, a change in the relative axial position of thetwo telescoped elements being effected by pulling the outer telescopicmember towards the upper limb member by means of a wire, cord or stringattached to the outer telescopic member. The free end of this wire orstring can be attached to a selected part of the body of the personhaving the artificial limb, so that, by tensioning the wire or string,the locking device is released and the two limb members are able to takeup a different relative angular position.

In order that the invention may be fully appreciated, a specific exampleof an artificial limb in accordance with it is shown in the accompanyingdrawing, in which:

FIG. 1 is a side view of the artificial limb, the upper limb memberbeing shown only partially;

FIG. 2 is an enlarged section through the telescopic link which formspart of the artificial limb shown in FIG. 1; and

FIG. 3 is a still further enlarged portion of the telescopic link shownin FIG. 2 illustrating the manner in which the locking device operates.

The artificial limb shown in FIG. 1 takes the form of an articulatedartificial arm comprising an upper limb member or upper arm 10 and alower limb member or lower arm 12 which are pivotally connected togetherby a transverse pivot pin 14 located in the lower part of the upper limbmember. The upper limb member 10 here comprises a cup-shaped lowersection 16 made, for example, of aluminium alloy or rigid syntheticplastics material, the lower part of this cup-shaped portion 16 beingbifurcated to receive one end of a metal rod 18 which .forms part of thelower limb member 12. The outer portion of the rod 18 is covered with asynthetic plastics foamed or sponge material or some other soft material20 shaped to resemble a fore-arm and a human hand.

It will thus be seen that the artificial arm shown in FIG. 1 providespivotal movement at 14 between the upper limb member 10 and the lowerlimb member 12 in the same way as the lower and upper arms in a humanarm are able to pivot about the elbow.

As indicated above, it is the main aim of the invention to provide meansby which the lower arm or limb member 12 can be locked in a number ofdifferent angular positions relatively to the upper arm or limb member10, and for this purpose the upper and lower limb members are linkedtogether by a telescopic link 22. This is pivotally attached to the rod18 at about its mid-portion by a pivotal connection 24 and, in a similarmanner, is pivotally connected at 26 to the upper limb member 10 at apoint some two or three inches above the pivot pin 14. The telescopiclink 22 comprises an outer tubular element 28 which, in this instance,is the part attached to the lower limb member 12, and an inner element30 in the form of a rod which is the part attached to the upper limbmember 10. As shown in FIG. 2, the inner element 30 extends into thetubular element 28, the two elements therefore being arranged fortelescopic movement in relation to each other.

In order to enable the lower limb member 12 to be locked in the mannerindicated above, the telescopic link 22 includes a locking devicewhereby the inner telescopic element or rod 30 may be locked in a numberof different axial positions relatively to the outer telescopic element28. The locking device here comprises two balls 32 which are arranged tobe seated in a series of transverse or annular grooves 34 formed in thatportion of the rod 30 which slides in the outer telescopic element 28.As will be seen, these transverse or annular grooves 34 are closelyspaced together. In order that the balls 32 may be released from theparticular grooves 34 in which they are seated, the outer telescopicelement 28 is provided with holes 36 covered by a resilient sleeve 38made of rubber or some other yielding material. Normally, however, thetwo telescopic elements 28, 30 are held in a locked position by theaction of a helical spring 40 which bears against an abutment 42attached to the rod 30 and against the upper end 44 of the outertelescopic element 28. The effect of this spring is to urge the edge 46bounding the holes 36 in the outer telescopic element 28 hard againstthe balls 32 (see FIG. 3) This inevitably traps the two balls in theparticular groove or grooves 34 where they are seated and thuseffectively locks the two elements 28, 30 against relative axialmovement. This, in turn, locks the lower limb member 12 against angularmovement relatively to the upper limb member 10.

For the purpose of releasing the locking device, a wire or string 48 isattached to a lug 50 on the outer surface of the outer telescopicelement 28, the free end of the wire or string 48 being passed round apulley 5-2 on the upper limb member and then taken to a part of the bodywhich can be moved so as to tension the wire or string 48. Accordingly,when the wire or string 48 is tensioned, it will pull the outertelescopic element 28 towards the abutment 42- on the rod 30 against theaction of the spring 40 and will permit the balls 32 to ride over theridges 54 separating the grooves 34 in the rod 30. As the balls 32. rideover the ridges, they are naturally forced radially outwards into theholes 32 and against the resilient sleeve 38 which yields to an extentsufiicient to allow the desired relative axial movement between the rod30 and the outer telescopic element 28. Directly, however, the wire orstring 48 is released, the spring 40 acts quickly to push the end 44 ofthe outer telescopic element 28 away from the abutment 42. This causesthe edge 46 (FIG. 3) to be forced against the balls in whatever grooveor grooves 34 they happen to be at that time. The telescopic elements28, 30 are now therefore locked against relative axial movement and thushold the upper and lower limb members 10, 1-2 in whatever angularposition they happend to be when the wire or string 48 was released.

It will be appreciated that the number of angular positions in which thelower limb member 12 can be locked in relation to the upper limb member10 is governed by the number of grooves 34 on the inner telescopicmember 30. Further, the angular distance over which the lower limbmember 12 moves as the balls 32 move from one groove 34 to the next isgoverned primarily by the size of the balls, the size of the grooves,and the distance between adjacent grooves. These dimensions cannaturally be selected to suit different requirements, but we have foundthat it is entirely acceptable to use balls of about /4" diameter withthe distance between the bottom portions of adjacent grooves being about/3" apart.

For reasons of strength, the telescopic link will normally be made ofmetal, for example aluminium alloy or some other stainless metal.

Although the specific artificial arm described above makes use oflocking balls 32 which cooperate with grooves 34 to lock the twoelements of the telescopic link against relative axial movement, it ispossible for other locking devices to be used instead. For example, apawl and ratchet mechanism can be provided whereby a springloaded pawlcooperates with a ratchet formed on the lower end of the rod 30. Itwould also be possible for the lower end of the rod 30 to be providedwith some kind of projection which is urged by a spring into any one ofa number of holes or serrations provided in the outer telescopic element28.

The invention has been described above with particular emphasis onarticulated artificial arms as this is the application where theinvention will normally be used, but it can also be applied toartificial legs and other artificial limbs where two members arepivotally connected together and need to be held in a number of relativeangular positions.

I claim:

1. An articulated artificial limb having two limb members, a pivotalconnection between the two limb members to permit relative pivotalmovement between them, a telescopic link comprising an outer telescopicelement and an inner telescopic element linking the two limb memberstogether at points displaced from the pivotal connection, and areadily-releasable locking device operable to lock the said twotelescopic elements in a number of different relative axial positions soas to lock the two limb members in a corresponding number of relativeangular positions, the said locking device comprising a plurality oftransverse grooves formed in that portion of the said inner telescopicelement which slides telescopically in the outer telescopic element, andat least one locking ball located in the outer telescopic element andarranged to seat in any one of the said transverse grooves.

2. An artificial limb as claimed in claim 1, wherein the locking ball islocated in a hole in the outer telescopic element, the hole beingcovered by a resilient sleeve so as to permit the ball to be releasedfrom the transverse groove in which it is seated in the innertelescopic-element.

References Cited UNITED STATES PATENTS 1,334,834 3/1920 Blatchford 3-22,834,024 5/1958 Aveni 3l2 3,407,409 10/ 1968 Prahl 327 OTHER REFERENCESOrthopaedic Appliances Atlas, vol. 2, artificial limbs, pp. 197, 198, J.W. Edwards, Ann Arbor, Mich, 1960.

RICHARD A. GAUDET, Primary Examiner J. YASKO, Assistant Examiner U.S.Cl. X.R. 3l2.2

